An Axial Compression Planar Lens Antenna Based on the Discrete Transformation Electromagnetics Using the High Impedance Surface Cells

A two-dimensional (2-D) convex lens is reshaped and compressed into a 2-D flat lens with a compression ratio of 52.6% by discrete transformation electromagnetics. The single-layer high-impedance surface cells are used to fill with the compressed zone to form a planar flat lens. A parallel-plate waveguide and a 1/4 λ reflector are used to ensure that the electromagnetic energy generated by the monopole flows to the lens. The planar lens antenna, 4.35 λ × 4 λ on the lens plane and 0.375 λ tall, is fabricated and measured in TM mode at 7.5 GHz. The measured data indicate that the proposed planar lens antenna achieves an 11.3 dBi gain, 16.7° half-power beamwidth on H -plane, and almost 260 MHz impedance bandwidth for S 11. The joint design of discrete transform electromagnetics and high-impedance surface cells is a new method, which has strong reference value for the miniaturization of other lens antennas.